Fibrous composites are promising lightweight, high-strength materials which retain their strength at high temperatures. The fibers contribute high tensile strength and crack propagation resistance to the refractory matrix and should not be bonded strongly to the matrix.
Fibrous composites can be prepared in a variety of ways. One method involves infiltrating the reinforcing fibers, disposed in a woven fabric or the like, with refractory materials or precursors thereof. In order to obtain composites of desired dimensions for different applications, especially of a desired thickness, layers of such woven fabric are stacked one on another.
This then presents the problem of introducing a sufficient quantity of the refractory material (or precursor thereof) into the interstices of a preform, such as stacked layers of woven fabric, which will provide the reinforcing structure of the composite. If the various fiber groupings of the stacked layers of woven fabric could be substantially completely infiltrated with refractory material precursors, and if the size of the pores within the fibrous composites could be minimized so that the matrix would substantially completely fill the interstices of the fiber groupings, an article of high strength should result.